Disable overflow tests

Disable tests about overflow when scrollable shelf is enabled.

Bug: 1002576
Change-Id: I248cc1261dc571eddcb4ef93982436f641f7d8bf
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1797043Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
Commit-Queue: Andrew Xu <andrewxu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#696057}

ash/shelf/shelf_unittest.cc

@@ -19,6 +19,7 @@
 #include "ash/test/ash_test_base.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/threading/thread_task_runner_handle.h"
+#include "chromeos/constants/chromeos_switches.h"
 #include "components/session_manager/session_manager_types.h"
 #include "mojo/public/cpp/bindings/associated_binding.h"
 
@@ -103,6 +104,11 @@ TEST_F(ShelfTest, CheckHoverAfterMenu) {
 }
 
 TEST_F(ShelfTest, ShowOverflowBubble) {
+  // No overflow bubble when scrollable shelf enabled.
+  // TODO(https://crbug.com/1002576): revisit when scrollable shelf is launched.
+  if (chromeos::switches::ShouldShowScrollableShelf())
+    return;
+
   ShelfWidget* shelf_widget = GetPrimaryShelf()->shelf_widget();
 
   // Add app buttons until overflow occurs.